The invention relates to a method for controlling an ignition system for internal combustion engines comprising at least one ignition output stage for the excitation of at least one ignition coil that generates a sparking current, and where the value of the sparking current and the sparking period can be set.
An ignition system of this kind is known from DE-OS 39 28 726 that has the advantage, compared with conventional ignition systems such as so-called transistorized ignition systems with inactive high-voltage distribution, of being able to employ small and therefore low-cost ignition coils. Furthermore, in accordance with the above-mentioned publication, optimum ignition is ensured because it remains switched on for the entire sparking period irrespective of engine speed. An ignition system of this kind is known as an alternating current ignition system because it generates a bipolar sparking current.
In the prior-art ignition concepts, the primary requirements were as follows: To ensure a reliable cold start and to reliably ignite the fuel/air mixture in the cylinder even if the spark plugs were sooty. In order to meet these requirements, a correspondingly large amount of ignition energy was made available. This ignition energy, which was designed to meet the maximum requirement of the engine, is not needed in normal operation (warm engine). Consequently, the electrode erosion of the spark plugs is unnecessarily high which in turn reduces the life of the spark plugs and results in frequent replacement of the spark plugs.